Media ratings and metering information is typically generated by collecting viewing records or other media consumption information from a group of statistically selected households. Each of the statistically selected households typically has a data logging and processing unit commonly referred to as a “home unit.” In households having multiple viewing sites (e.g., multiple television systems or, more generally, multiple media presentation devices), the data logging and processing functionality may be distributed among a single home unit and multiple site units, where one site unit may be provided for each viewing site, location or area. The home unit (or the combination of the home unit and the site units) is often in communication with a variety of attachments that provide inputs to the home unit or receive outputs from the site unit to gather data from the audio-video (AV) devices at the selected site.
Available AV devices are becoming more complex in functionality and interoperability with other AV devices. As a result, manufacturers are exploring new, user-friendly ways of standardizing interfaces to simplify for the user the set-up and operation of these devices. For example, High-Definition Multimedia Interface-Consumer Electronic Control (HDMI-CEC) simplifies the setup and operation of an otherwise complex arrangement of AV network devices
An AV network configured in this manner is typically monitored using hardware, firmware, and/or software to interface with the AV devices to extract or to generate signal information that may be used to determine viewing habits. Many AV networks are also configured so that the AV devices coupled to the network may be powered independently. As a result, a set top box, for example, may be powered on while a television associated with the set top box is off. Thus, monitoring AV networks having independently powered devices typically involves an additional device or method to determine the operating state of the television set to ensure that the collected data reflects media information actually viewed or consumed.
In addition, building security and building monitoring systems, which may use a variety of AV devices, are becoming more prevalent. Such systems enable a building owner to determine the state of various electronic appliances in the building, even when the building owner is located remotely from the building premises. In many instances, the building owner may desire to know the operating state, e.g., on state or off state, of a particular appliance such as a television or other media delivery/presentation device. In another setting, parents often have an interest in monitoring their children's television viewing habits, electronic gaming habits, and computer usage habits. A component of monitoring such habits involves determining the on or off state of the appliance, electronic device, etc. of interest.